JP2012145177A - Aluminum tube joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable aluminum tube joint excellent in mass productivity.SOLUTION: The aluminum tube joint includes a first aluminum tube 1 in which a diameter expanded part 5 is formed at its end through a tapered part 4 whose diameter expands as it advances to the end, and a second aluminum tube 2 whose outer diameter is smaller than the inner diameter of the diameter expanded part 5, and larger than the minimum inner diameter of the tapered part 4, the second aluminum tube 2 and the first aluminum tube 1 being brazed with an aluminum brazing filler 3 in a state that the end of the second aluminum tube 2 is inserted into the diameter expanded part 5 of the first aluminum tube 1. A plurality of convex parts 6a are provided circumferentially on the inner periphery of the diameter expanded part 5, which prevent the leading end of the second aluminum tube 2 from coming into contact with the tapered part 4 by abutting against part of the leading end of the second aluminum tube 2 in such a manner that the center of the diameter expanded part 5 roughly coincides with the center of the tube at the leading end of the second aluminum tube 2 when a cross-section surface of the diameter expanded part 5 at the leading end position of the second aluminum tube 2 is viewed.

Description

  The present invention is an aluminum used as a pipe joint obtained by joining a part of aluminum refrigerant pipes of a cooler (evaporator) in the field of a refrigerator for refrigerators for home use or commercial use, and also a showcase, for example. It relates to pipe joints.

  For joining the aluminum tubes, TIG welding (tungsten-inert gas welding), aluminum brazing and aluminum brazing using a non-corrosive flux, so-called nocolok flux brazing, or the like is generally used.

  TIG welding is still often used for joining aluminum refrigerant tubes in refrigerators in the field of refrigeration equipment. Since the coolers in this field are used in a state where moisture is repeatedly frozen and thawed, the current situation is that aluminum brazing is not actively used because there is a high possibility that voids are generated at the joints of aluminum tubes. .

  When applied to a refrigerator for freezing and refrigeration, when moisture enters through a void, a phenomenon called freeze puncture is caused and the airtightness of the joint is lowered. Voids are likely to occur when the soldering is poor, when the flux used is entrained in the wax, or when the generated gas is entrained in the wax, and the cause is affected by the temperature balance and joint shape. There are many.

  However, compared to TIG welding, aluminum brazing can produce joints with excellent airtightness, so that producing joints with as few voids as possible is the point of applying aluminum brazing in this field. It becomes.

  As an example of a conventional joint shape, there is an aluminum pipe joint that is brazed with an aluminum pipe having the same diameter inserted into an aluminum pipe having an enlarged diameter portion at an end (see, for example, Patent Document 1).

  8 to 12 show a conventional aluminum pipe joint described in Patent Document 1 described above. 8 is a longitudinal cross-sectional view of a conventional aluminum pipe joint cut along a plane including the pipe axis, FIG. 9 is a cross-sectional view taken along line AA of FIG. 8, and FIG. 10 is a conventional aluminum pipe in a state before brazing. It is a partially cutaway longitudinal cross-sectional view at the time of cutting out a joint partially in the plane containing a pipe axis.

  FIG. 11 is a vertical cross-sectional view of a conventional aluminum pipe joint in a state where an outer sagging defect with the wax hanging outwards is cut along a plane including the pipe axis, and FIG. It is a longitudinal cross-sectional view at the time of cut | disconnecting the conventional aluminum pipe joint in the state in which the sagging internal defect has generate | occur | produced in the plane containing a pipe axis.

  The conventional aluminum pipe joint includes a first aluminum pipe 1 in which an enlarged diameter portion 5 is formed at an end portion through a tapered portion 4 whose diameter increases toward the end portion, and an outer diameter of the enlarged diameter portion 5. The second aluminum tube 2 is smaller than the inner diameter of the taper portion 4 and larger than the minimum inner diameter of the taper portion 4, and the end of the second aluminum tube 2 is inserted into the expanded diameter portion 5 of the first aluminum tube 1. Thus, the second aluminum pipe 2 and the first aluminum pipe 1 are joined by the aluminum brazing 3.

Before brazing, the aluminum braze 3 is a ring-shaped ring braze 7 at the upper portion of the interface between the outer peripheral surface of the end of the second aluminum tube 2 in the enlarged diameter portion 5 and the inner peripheral surface of the enlarged diameter portion. It is set. The ring solder 7 has a ring shape that is smaller than the outer diameter of the enlarged diameter portion 5 and has an inner diameter that is equal to or larger than the outer diameter of the second aluminum tube 2, and is composed of a brazing material 7a and a flux 7b.

  About the conventional aluminum pipe joint comprised as mentioned above, the manufacturing method is demonstrated below.

  As shown in FIG. 10, first, the first aluminum tube 1 has an end portion where the enlarged diameter portion 5 is formed facing upward in the vertical direction, and the end portion of the second aluminum tube 2 is the first aluminum tube 1. While being inserted into the enlarged diameter portion 5, the ring braze 7 is set so as to surround the second aluminum tube 2 and rest on the end portion where the enlarged diameter portion 5 of the first aluminum tube 1 is formed.

  Next, by heating the vicinity of the ring brazing 7 by a heating means (not shown), the entire temperature is raised, the flux 7b having the lowest melting point is melted, and the brazing material 7a and the first aluminum tube 1 The aluminum oxide film present at the joint interface of the second aluminum tube 2 is removed.

  Next, the brazing filler metal 7a having a low melting point is melted and filled and diffused at the joint interface between the outer peripheral surface of the end of the second aluminum tube 2 in the enlarged diameter portion 5 and the inner peripheral surface of the enlarged diameter portion. Thus, the first aluminum tube 1 and the second aluminum tube 2 are brazed. When the first aluminum tube 1 and the second aluminum tube 2 are ideally brazed, the state shown in FIG. 8 is obtained.

  However, in the temperature raising process by the heating means, a slight variation in thickness between the first aluminum tube 1 and the second aluminum tube 2 and the second inserted into the enlarged diameter portion 5 of the first aluminum tube 1 are performed. It changes depending on a slight difference in the insertion dimension of the aluminum tube 2.

  FIG. 11 shows an outer sagging defect state of the aluminum brazing 3 in which the brazing aluminum sagging 3a is generated by dripping the aluminum brazing 3 outside the enlarged diameter portion 5. The wax outer sagging 3a is often generated when the end of the second aluminum tube 2 is in contact with the inner peripheral surface of the tapered portion 4 of the first aluminum tube 1, and the first aluminum tube 1 and the second aluminum tube 2 are in contact with each other. The aluminum solder 3 is not so much filled in the joining interface of the aluminum tube 2, and the joining strength is lowered.

  FIG. 12 shows an internal dripping defect of the aluminum brazing 3 in which the brazing aluminum sagging 3b is generated by dripping the aluminum brazing 3 from the enlarged diameter portion 5 to the inner peripheral surface of the taper portion 4. This sagging defect occurs when the heating of the second aluminum tube 2 by the heating means during the specified time is too fast, and as a result, a through hole 8 due to overbaking occurs in the second aluminum tube 2. The airtightness is reduced.

  Therefore, conventionally, the end of the second aluminum tube 2 is such that the end of the second aluminum tube 2 passes through the enlarged diameter portion 5 of the first aluminum tube 1 and does not contact the inner peripheral surface of the tapered portion 4. Brazing is performed in a state where the end portion is inserted into the enlarged diameter portion 5 of the first aluminum tube 1, and the end portion of the second aluminum tube 2 is slightly larger than the enlarged diameter portion 5 of the first aluminum tube 1. By raising the temperature by the heating means so that the temperature rises quickly, the generation of the through-holes 8 due to the outer sagging 3a, the inner sagging 3b and the overbaking is suppressed, and the joining strength and the air tightness are ensured. Yes.

JP 9-174233 A

  However, in the conventional configuration, the end portion of the second aluminum tube 2 is placed in the first aluminum tube 2 so that the end portion of the second aluminum tube 2 does not contact the inner peripheral surface of the tapered portion 4 of the first aluminum tube 1. In order to make the state inserted in the enlarged diameter part 5 of the aluminum tube 1, it is necessary to fix the 1st aluminum tube 1 and the 2nd aluminum tube 2 with a predetermined insertion dimension.

  By the way, in general, there are variations in the length of the aluminum pipe, and even if the first aluminum pipe 1 and the second aluminum pipe 2 are fixed, the insertion dimension is not always determined at a predetermined position. If the insertion dimension is shorter than the predetermined dimension, overbaking is likely to occur, and if the insertion dimension is longer than the predetermined dimension, it is likely that brazing will occur. was there. Therefore, there is a problem that a defective product having a problem in bonding strength and airtightness may occur during mass production.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide an aluminum pipe joint that is unlikely to generate defective products having problems in bonding strength and airtightness during mass production.

  In order to achieve the above-mentioned object, the present invention provides the above-mentioned diameter expansion when the section of the diameter-enlarged portion at the tip position of the second aluminum tube is viewed on the inner peripheral surface of the diameter-enlarged portion of the first aluminum tube. The tip of the second aluminum tube is in contact with a part of the tip of the second aluminum tube so that the center of the portion substantially coincides with the center of the tube of the tip of the second aluminum tube. A plurality of convex portions for preventing contact with the circumferential surface are provided in the circumferential direction.

  As a result, the second aluminum tube can be formed on the plurality of convex portions on the inner peripheral surface of the enlarged diameter portion of the first aluminum tube without providing a means for fixing the positional relationship between the first aluminum tube and the second aluminum tube. By simply inserting the tip of the second aluminum tube into the diameter-expanded portion of the first aluminum tube until the tip of the second aluminum tube abuts, the tip of the second aluminum tube is within the tapered portion 4 of the first aluminum tube 1. The center of the tube at the tip of the second aluminum tube can be made substantially coincident with the center of the enlarged diameter portion at a predetermined position away from the peripheral surface.

  Furthermore, if the shape of the protrusions and the number of protrusions are set appropriately so that the total contact area of the contact portions between the tip of the second aluminum tube and the plurality of protrusions does not become too large, an ideal rise is obtained. A temperature process can be realized.

  Therefore, since it is possible to provide an aluminum pipe joint that can reliably ensure bonding strength and airtightness during mass production, it is possible to provide a highly reliable aluminum pipe joint, a cooler using the same, and a refrigerator-freezer. it can.

  In the aluminum pipe joint of the present invention, the tip of the second aluminum pipe is moved to the first aluminum pipe until the tip of the second aluminum pipe comes into contact with the plurality of convex portions on the inner peripheral surface of the enlarged diameter portion of the first aluminum pipe. It is possible to achieve the ideal temperature rise process by simply inserting the aluminum pipe into the enlarged diameter part of the aluminum pipe and positioning the tip of the second aluminum pipe in place. The joint strength of mass-produced aluminum pipe joints In addition, it is possible to provide a highly reliable aluminum pipe joint, a cooler using the aluminum pipe joint, and a refrigeration and refrigeration equipment that is reliably secured.

The longitudinal cross-sectional view at the time of cut | disconnecting the aluminum pipe joint in Embodiment 1 of this invention by the plane containing a pipe axis BB sectional view of FIG. CC sectional view of FIG. The longitudinal cross-sectional view at the time of cut | disconnecting the aluminum pipe joint in Embodiment 2 of this invention by the plane containing a pipe axis DD sectional view of FIG. The longitudinal cross-sectional view at the time of cut | disconnecting the aluminum pipe joint in Embodiment 3 of this invention by the plane containing a pipe axis EE sectional view of FIG. Longitudinal sectional view of a conventional aluminum pipe joint cut by a plane including the pipe axis AA sectional view of FIG. Partially cutaway longitudinal sectional view when a conventional aluminum pipe joint in a state before brazing is cut out partially on a plane including the pipe axis Longitudinal cross-sectional view of a conventional aluminum pipe joint in a state where an outer sagging defect with the wax hanging outwards is cut along a plane including the pipe axis Longitudinal cross-sectional view of a conventional aluminum pipe joint in a state where an internal sagging defect with the wax hanging inside is cut along a plane including the pipe axis

  According to a first aspect of the present invention, there is provided a first aluminum tube in which an enlarged diameter portion is formed at the end portion via a tapered portion whose diameter increases toward the end portion, and an outer diameter smaller than an inner diameter of the enlarged diameter portion. And a second aluminum tube larger than the minimum inner diameter of the taper portion, and the second aluminum tube is inserted into the enlarged diameter portion of the first aluminum tube, and the second aluminum tube is inserted into the second aluminum tube. An aluminum pipe joint in which an aluminum pipe and the first aluminum pipe are brazed, and a cross section of the enlarged diameter portion at a tip position of the second aluminum pipe is seen on an inner peripheral surface of the enlarged diameter section. The second aluminum tube in contact with a part of the tip of the second aluminum tube so that the center of the enlarged diameter portion substantially coincides with the center of the tube at the tip of the second aluminum tube. The tip of the taper Aluminum pipe joint being characterized in that a plurality of convex portions in the circumferential direction to prevent the touch.

  With the above configuration, the second aluminum is formed on the plurality of convex portions on the inner peripheral surface of the diameter-enlarged portion of the first aluminum tube without providing a means for fixing the positional relationship between the first aluminum tube and the second aluminum tube. Simply insert the tip of the second aluminum tube into the enlarged diameter portion of the first aluminum tube until the tip of the tube abuts, and the tip of the second aluminum tube will move to the inner circumference of the taper portion of the first aluminum tube. The center of the tube at the tip of the second aluminum tube can be made substantially coincident with the center of the enlarged diameter portion at a predetermined position away from the surface.

  Furthermore, if the shape of the protrusions and the number of protrusions are set appropriately so that the total contact area of the contact portions between the tip of the second aluminum tube and the plurality of protrusions does not become too large, an ideal rise is obtained. A temperature process can be realized.

  Therefore, since it is possible to provide an aluminum pipe joint that can reliably ensure bonding strength and airtightness during mass production, it is possible to provide a highly reliable aluminum pipe joint, a cooler using the same, and a refrigerator-freezer. it can.

  According to a second aspect of the present invention, in the first aspect of the invention, the outer peripheral surface of the enlarged diameter portion of the first aluminum pipe is provided with a substantially arc-shaped recess by dimple processing on the inner peripheral surface of the enlarged diameter portion. A convex portion is provided, and a predetermined portion of the outer peripheral surface of the enlarged diameter portion of the first aluminum tube is pressed inward with a dimple processing pin, thereby forming an inner peripheral surface of the enlarged diameter portion of the first aluminum tube. A plurality of convex portions can be easily provided.

According to a third aspect of the invention, in the first aspect of the invention, the convex portion is provided on the inner peripheral surface of the enlarged diameter portion by providing a non-expanded diameter portion when forming the enlarged diameter portion of the end portion of the first aluminum tube. And
In the step of processing the enlarged diameter portion, the convex portion can be processed at the same time, and productivity can be improved.

  According to a fourth aspect of the present invention, in the first aspect of the invention, when a pipe having a plurality of grooves in the tube length direction on the inner surface is used as the first aluminum pipe, the end of the first aluminum pipe is expanded. The convex portion is inevitably formed by the diameter-expansion processing so as to eliminate the groove to the position where the tip position of the second aluminum tube is inserted.

  With the above configuration, in the step of expanding the diameter of the end portion of the first aluminum tube, a plurality of convex portions can be provided on the inner peripheral surface of the expanded diameter portion of the first aluminum tube at the same time. Since the thickness of the aluminum tube in contact with each other becomes substantially the same and the joining interface can be filled with substantially the same amount of aluminum brazing, it can be joined under substantially the same heating conditions as the grooveless tube.

  Therefore, it is not necessary to change the joining conditions due to the presence or absence of grooves, and it is not necessary to change the switching loss or the aluminum brazing in the process.

  Hereinafter, embodiments of the aluminum pipe joint of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, about the same structure as the past, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

(Embodiment 1)
1 is a longitudinal sectional view of an aluminum pipe joint according to Embodiment 1 of the present invention cut along a plane including a pipe axis, FIG. 2 is a sectional view taken along line BB in FIG. 1, and FIG. It is CC sectional drawing.

  As shown in FIGS. 1, 2, and 3, the aluminum pipe joint according to the present embodiment has a diameter-expanded portion 5 formed at the end via a tapered portion 4 whose diameter increases toward the end. The first aluminum tube 1 and the second aluminum tube 2 whose outer diameter is smaller than the inner diameter of the enlarged diameter portion 5 and larger than the minimum inner diameter of the tapered portion 4, and the end of the second aluminum tube 2 is the first The second aluminum tube 2 and the first aluminum tube 1 are brazed with an aluminum braze 3 while being inserted into the enlarged diameter portion 5 of the aluminum tube 1.

  In addition, the aluminum pipe joint in the present embodiment is expanded by providing substantially arc-shaped concave portions by pressing (dimple processing) at a plurality of predetermined positions on the outer peripheral surface of the enlarged diameter portion 5 of the first aluminum tube 1. The center of the enlarged diameter portion 5 when the cross section of the enlarged diameter portion 5 at the distal end position of the second aluminum tube 2 is seen on the inner peripheral surface of the diameter portion 5 is the center of the tube at the distal end of the second aluminum tube 2. A plurality of convex portions 6 a are provided in the circumferential direction so as to substantially coincide with each other and prevent the tip of the second aluminum tube 2 from contacting the tapered portion 4 by contacting a part of the tip of the second aluminum tube 2. Yes.

  About the aluminum pipe joint of this Embodiment comprised as mentioned above, the manufacturing method and an effect | action are demonstrated below.

  First, a ring solder 7 is attached in the vicinity of the tip of the second aluminum tube 2, and the second aluminum tube 2 is formed on the plurality of convex portions 6 a formed on the inner peripheral surface of the diameter-enlarged portion 5 of the first aluminum tube 1. The tip of the second aluminum tube 2 is inserted into the enlarged diameter portion 5 of the first aluminum tube 1 until the tip of the first aluminum tube 1 abuts.

At this time, even if a means for fixing the positional relationship between the first aluminum tube 1 and the second aluminum tube 2 is not taken, the plurality of convex portions 6a on the inner peripheral surface of the enlarged diameter portion 5 of the first aluminum tube 1 are formed. By simply inserting the tip of the second aluminum tube 2 into the enlarged diameter portion 5 of the first aluminum tube 1 until the tip of the second aluminum tube 2 comes into contact, the tip of the second aluminum tube 2 is The center of the tube at the tip of the second aluminum tube 2 can be made substantially coincident with the center of the enlarged diameter portion 5 at a predetermined position away from the inner peripheral surface of the tapered portion 4 of the one aluminum tube 1.

  In addition, the shape of the convex part 6a and the number of convex parts 6a are set so that the total contact area of the contact part of the front-end | tip of the 2nd aluminum tube 2 and the some convex part 6a may not become large too much. Further, the distance between the convex portion 6 a and the central axis of the enlarged diameter portion 5 is made shorter than half the outer diameter (diameter) of the tip of the second aluminum tube 2.

  The first aluminum tube 1 has an end portion on which the enlarged diameter portion 5 is formed facing upward in the vertical direction, and the ring braze 7 surrounds the second aluminum tube 2 to form the enlarged diameter portion 5 of the first aluminum tube 1. Set it so that it rests on the edge. Gravity can be used to maintain the positional relationship between the first aluminum tube 1, the second aluminum tube 2, and the ring solder 7.

  Next, when the heating means (not shown) is used to heat the vicinity of the ring brazing 7, the temperature of the upper part of the second aluminum tube 2 is raised first from the ring brazing 7, and the lower part is also heated in order. In the process, the diameter-expanded portion 5 of the first aluminum tube 1 is also heated.

  Next, the flux 7b reaches the melting point and liquefies, but flows downward due to the influence of gravity, and flows to the first aluminum pipe 1 side where the temperature is most increased, and flows into the expanded diameter portion 5 Then, the oxide film is removed by the action of the flux.

  Next, the brazing material 7a reaches the melting point and liquefies, flows into the enlarged diameter portion 5, the silicon Si component contained in the brazing material 7a diffuses into the aluminum, and liquefies by finishing the heating. The brazing filler metal 7a and the flux 7b are solidified and the aluminum brazing filler 3 is filled in the joining interface.

  At this time, the total contact area of the contact portion between the convex portion 6a and the tip of the second aluminum tube 2 is small, and the heat of the second aluminum tube 2 that is first heated is directed to the first aluminum tube 1 side. Since the escape rate is very small, the speed at which the second aluminum pipe 2 is heated is faster than the speed at which the diameter-expanded portion 5 of the first aluminum pipe 1 is heated from the outside to raise the temperature. There is very little chance that 3 will sag.

  Of course, since the target position of the heating is also near the tip of the enlarged diameter portion 5, the possibility of overbaking is minimized.

  As described above, the aluminum pipe joint of the present embodiment is provided with substantially arc-shaped concave portions by pressing (dimple processing) at a plurality of predetermined positions on the outer peripheral surface of the enlarged diameter portion 5 of the first aluminum tube 1. The center of the enlarged diameter portion 5 when the section of the enlarged diameter portion 5 at the tip position of the second aluminum tube 2 is viewed on the inner peripheral surface of the enlarged diameter portion 5 is the tube at the tip of the second aluminum tube 2. A plurality of convex portions 6a in the circumferential direction are provided in contact with a part of the tip of the second aluminum tube 2 to prevent the tip of the second aluminum tube 2 from contacting the tapered portion 4 so as to substantially coincide with the center. It is provided.

  With the above configuration, a plurality of convex portions 6a on the inner peripheral surface of the enlarged diameter portion 5 of the first aluminum tube 1 can be obtained without providing a means for fixing the positional relationship between the first aluminum tube 1 and the second aluminum tube 2. By simply inserting the tip of the second aluminum tube 2 into the enlarged diameter portion 5 of the first aluminum tube 1 until the tip of the second aluminum tube 2 comes into contact, The center of the tube at the tip of the second aluminum tube 2 can be made substantially coincident with the center of the enlarged diameter portion 5 at a predetermined position away from the inner peripheral surface of the tapered portion 4 of the first aluminum tube 1.

Furthermore, if the shape of the convex portion 6a and the number of the convex portions 6a are appropriately set so that the total contact area of the contact portions between the tip of the second aluminum tube 2 and the plurality of convex portions 6a is not too large, It is possible to realize an ideal temperature rising process.

  Therefore, since it is possible to provide an aluminum pipe joint that can reliably ensure bonding strength and airtightness during mass production, it is possible to provide a highly reliable aluminum pipe joint, a cooler using the same, and a refrigerator-freezer. it can.

  Further, by providing substantially arc-shaped concave portions by pressing (pressing inward with dimple processing pins) at a plurality of predetermined positions on the outer peripheral surface of the enlarged diameter portion 5 of the first aluminum tube 1, the first aluminum A plurality of convex portions 6 a can be easily provided on the inner peripheral surface of the enlarged diameter portion 5 of the tube 1.

(Embodiment 2)
4 is a longitudinal sectional view of the aluminum pipe joint according to the second embodiment of the present invention cut along a plane including the pipe axis, and FIG. 5 is a DD sectional view of FIG.

  As shown in FIGS. 4 and 5, the aluminum pipe joint in the present embodiment is similar to the aluminum pipe joint in the first embodiment through the tapered portion 4 whose diameter increases toward the end portion. And a second aluminum tube 2 whose outer diameter is smaller than the inner diameter of the enlarged diameter portion 5 and larger than the minimum inner diameter of the tapered portion 4. The second aluminum tube 2 and the first aluminum tube 1 are brazed with the aluminum brazing 3 with the end of the aluminum tube 2 inserted into the enlarged diameter portion 5 of the first aluminum tube 1. .

  In addition, the aluminum pipe joint in the present embodiment is provided with a second non-expanded portion at the time of forming the enlarged diameter portion 5 at the end of the first aluminum tube 1, thereby providing a second The second aluminum tube 2 so that the center of the enlarged diameter portion 5 when viewing the cross section of the enlarged diameter portion 5 at the distal end position of the aluminum tube 2 substantially coincides with the center of the tube at the distal end of the second aluminum tube 2. A plurality of convex portions 6 b are provided in the circumferential direction to contact a part of the tip of the second aluminum tube 2 and prevent the tip of the second aluminum tube 2 from contacting the tapered portion 4.

  About the aluminum pipe joint of this Embodiment comprised as mentioned above, the manufacturing method and an effect | action are demonstrated below.

  As shown in FIG. 4, in the step of expanding the diameter of the first aluminum tube 1, a tube expansion pin (not shown) having an outer diameter slightly larger than the outer diameter of the second aluminum tube 2 is used as the first aluminum tube 1. However, the enlarged diameter portion 5 and the non-expanded diameter portion have the same circumference by making the cross-sectional shape of a certain section from the tip of the tube expansion pin into an irregular shape as shown in FIG. Can be formed on top.

  That is, in addition to the effects of the first embodiment, only the step of expanding the diameter of the end portion of the first aluminum tube 1 is performed, and at the same time, a plurality of the inner peripheral surfaces of the expanded diameter portion 5 of the first aluminum tube 1 are provided. The convex part 6b can be provided and productivity can be improved. It should be noted that the first aluminum tube is expanded with a tube expansion pin so that the distance between the convex portion 6b and the central axis of the expanded diameter portion 5 is shorter than half the outer diameter (diameter) of the tip of the second aluminum tube 2. The enlarged diameter portion 5 and the non-expanded diameter portion are formed at one end portion.

(Embodiment 3)
FIG. 6 is a longitudinal sectional view of the aluminum pipe joint according to Embodiment 3 of the present invention cut along a plane including the pipe axis, and FIG. 7 is an EE sectional view of FIG.

As shown in FIGS. 6 and 7, the aluminum pipe joint in the present embodiment is a tapered part 4 whose diameter increases toward the end, similarly to the aluminum pipe joint in the first and second embodiments. A first aluminum tube 1 having an enlarged diameter portion 5 formed at the end thereof, and a second aluminum tube 2 whose outer diameter is smaller than the inner diameter of the enlarged diameter portion 5 and larger than the minimum inner diameter of the tapered portion 4. The second aluminum tube 2 and the first aluminum tube 1 are made of aluminum brazing 3 with the end of the second aluminum tube 2 inserted into the enlarged diameter portion 5 of the first aluminum tube 1. It is brazed.

  Moreover, when the aluminum pipe joint in this Embodiment uses the pipe | tube by which the groove | channel of the pipe length direction was processed in the inner surface as the 1st aluminum pipe 1, and expands the edge part of the 1st aluminum pipe 1, By expanding the diameter so that there is no groove until the tip position of the second aluminum tube 2 is inserted, the diameter of the second aluminum tube 2 at the tip position of the second aluminum tube 2 is increased on the inner peripheral surface of the expanded diameter portion 5. When the cross section of the portion 5 is viewed, the diameter-enlarged portion 5 is in contact with a part of the tip of the second aluminum tube 2 so that the center of the enlarged portion 5 substantially coincides with the center of the tip of the second aluminum tube 2. A plurality of convex portions 6 c that prevent the tip of the second aluminum tube 2 from contacting the tapered portion 4 are provided in the circumferential direction.

  About the aluminum pipe joint of this Embodiment comprised as mentioned above, the manufacturing method and an effect | action are demonstrated below.

  As shown in FIGS. 6 and 7, the first aluminum tube 1 is an internally grooved tube. In the diameter expansion process, the clearance between the tube expansion pin and the outer diameter clamp mold is adjusted so that Processing can be performed so that the groove on the inner surface is eliminated from the tip to the position where the tip of the second aluminum tube 2 is inserted into the enlarged diameter portion 5 of the first aluminum tube 1. In addition, the inner surface of the first aluminum tube 1 so that the distance between the convex portion 6c and the central axis of the enlarged diameter portion 5 is shorter than half the outer diameter (diameter) of the tip of the second aluminum tube 2. Grooves are formed in

  Therefore, in the step of expanding the diameter of the end portion of the first aluminum tube 1, not only can the plurality of convex portions 6c be provided on the inner peripheral surface of the expanded diameter portion 5 of the first aluminum tube 1 simultaneously, Since the thickness of the aluminum tube in contact with the bonding interface is substantially the same and the bonding interface can be filled with approximately the same amount of aluminum brazing 3, it is possible to bond under substantially the same heating conditions as the grooveless tube. it can.

  Therefore, it is not necessary to change the joining conditions depending on the presence or absence of grooves, and it is not necessary to change the switching loss or the aluminum brazing 3 in the process.

  The aluminum pipe joint of the present invention is a highly reliable aluminum pipe joint that ensures the joining strength and airtightness of mass-produced aluminum pipe joints, so that it can be used for household or commercial refrigerators, and even showcases. It can be widely used for a cooler used in a refrigerator-freezer.

DESCRIPTION OF SYMBOLS 1 1st aluminum pipe 2 2nd aluminum pipe 3 Aluminum brazing 4 Tapered part 5 Expanded diameter part 6a, 6b, 6c Convex part

Claims (4)

A first aluminum tube having a diameter-expanded portion formed at the end portion through a tapered portion whose diameter increases toward the end portion; and a minimum outer diameter of the tapered portion, the outer diameter being smaller than the inner diameter of the diameter-expanded portion A second aluminum tube having a larger inner diameter, wherein the second aluminum tube and the first aluminum tube are inserted with the end portion of the second aluminum tube inserted into the enlarged diameter portion of the first aluminum tube. The aluminum pipe joint is brazed to the aluminum pipe, and the enlarged diameter when the cross section of the enlarged diameter portion at the tip position of the second aluminum pipe is viewed on the inner peripheral surface of the enlarged diameter section. The tip of the second aluminum tube is in contact with a part of the tip of the second aluminum tube so that the center of the portion substantially coincides with the center of the tube of the tip of the second aluminum tube. Prevent contact with Aluminum fittings, characterized in that a plurality of convex portions in the circumferential direction. 2. The convex portion is provided on the inner peripheral surface of the enlarged diameter portion by providing a substantially arc-shaped concave portion by dimple processing on the outer peripheral surface of the enlarged diameter portion of the first aluminum tube. The aluminum pipe joint described in 1. 2. The aluminum pipe according to claim 1, wherein the convex portion is provided on an inner peripheral surface of the enlarged diameter portion by providing a non-increased portion when forming the enlarged diameter portion of the first aluminum tube end portion. Fittings. When a tube having a plurality of grooves in the tube length direction on the inner surface is used as the first aluminum tube, the tip position of the second aluminum tube is inserted when the end of the first aluminum tube is expanded. The aluminum pipe joint according to claim 1, wherein the convex portion is inevitably formed by performing diameter expansion processing so as to eliminate the groove to a position.

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